The present invention relates to refrigerant vapor compression heat pump systems that are driven by combustion engine prime movers. More particularly, it relates to the integration of heat recovery, engine cooling, engine oil warming, engine oil cooling, and auxiliary heating functions in one space and cost saving device.
Vapor compression heat pumps are widely used to provide heating and cooling air conditioning in residential service. While the predominant motive power for such heat pump systems has been electric motor drive means, combustion engines are attractive alternative sources of motive power for such systems, and have been used in such settings.
One drawback of vapor compression heat pump systems has been that during winter operation the heating capacity decreases as the ambient temperature of the outside air, being used as a source of heat, goes down. At the same time, building heat losses increase, and under some conditions the temperature of the inside living space decreases unless some additional source of heat is available. A common solution to the problem has been the provision of auxiliary electric heaters to meet the requirements of the total heating load during severe outside temperature and weather conditions.
One of the advantages of using a combustion engine heat pump system is the excess heat of combustion generated in the engine which is available for wintertime heating augmentation. This reduces the requirement for auxiliary heaters. Thus, it is a common practice in combustion engine heat pump systems to recover the unused, excess heat from the engine by conveying a working fluid such as water with an ethylene glycol antifreeze through the cooling system of the engine and also through an exhaust gas heat exchanger where waste heat from the engine is exchanged with the working fluid. The working fluid is then conveyed or pumped to another heat exchanger or radiator that is located in the air flow in the air conditioned building. Where more severe weather requires further heat input, a separate auxiliary heater can be used to further heat the working fluid or air flow. One such system is shown, for example, in U.S. Pat. No. 5,003,788, to Fischer. In the '788 patent, in less severe weather conditions or in the cooling mode, the working fluid is conveyed to a hot water tank to heat water for domestic hot water service, and during the cooling mode, is further conveyed to an outdoor heat exchanger to reject heat to the atmosphere.
While the advantages of using waste heat from combustion engine driven heat pump systems is well recognized, the wide range of options for recovery and use of waste heat, such as disclosed in the '788 patent, has required numerous separate components for heat exchange, auxiliary heating and heat rejection to inside or environmental air flows. The complexity, size and cost of the heat pump systems having desirable heat recovery and use capabilities have increased accordingly.
Accordingly, the need exists for heat pump systems which recover and apply this heat in one space and cost saving device performing all recovery and auxiliary heating functions for combustion engine driven refrigerant vapor compression heat pump systems.